This study is being conducted to assess the effect of indacaterol (150 μg o.d.) on inspiratory capacity (IC), using placebo and open label tiotropium (18 μg o.d.) as comparators in patients with moderate chronic obstructive pulmonary disease (COPD). In particular, spirometric timepoints are included to elucidate the peak-IC in a period of approximately 4 hour post inhalation